Heraclitus was famous for his provocative sayings. For example: you can't step in the same river twice; dogs bark at what they don't understand; expect the unexpected, or you won't find it, because it leaves no trail. Today, more than 2500 years after they were written, his ideas about life, nature and the cosmos remain as startlingly original as ever. Roger von Oech uses 30 of Heraclitus's epigrams as a springboard to innovation. Treating each saying as a creativity exercise, he supplies mental puzzles, amusing anecdotes and intriguing questions designed to topple old habits of thought and fire the imagination.